Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

825
FXUS63 KLOT 131120
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
620 AM CDT Wed May 13 2026

.KEY MESSAGES...

- After a relatively cool Wednesday, temperatures will trend
  upward Thursday onward.

- Several rounds of showers and storms are possible in the
  general region this weekend into early next week, some could
  be severe.

&&

.DISCUSSION...
Issued at 317 AM CDT Wed May 13 2026

A much cooler airmass is moving overhead this morning on breezy
northwest winds following yesterday evenings cold frontal
passage. This unseasonably cool airmass in combination with a
good amount of strato-cu cloud cover will result in high
temperatures this afternoon only topping out in the low to mid
60s across inland portions of northern IL and northwest IN. Even
cooler conditions are expected along the Lake Michigan
lakeshore, where readings look to remain in the 50s this
afternoon as winds veer off the lake.

The winds will remain breezy through the day, with gusts of
20-25 mph expected. Wind speeds are then slated to abate with
sunset early this evening, then become light (<5 mph) overnight
as a surface ridge of high pressure shifts overhead. Light winds
under this high, in combination with clearing skies through the
evening, will set the stage for another chilly night. Overnight
temperatures are forecast to fall off into the upper 30s to low
40s inland from the lake and outside of Chicago. Some of the
typically climatologically favored cool spots could even drop a
bit lower (into the middle 30s), possibly resulting in some
patchy frost development towards early Thursday morning.
Fortunately, at this time, it appears the frost threat will
remain limited, so we will forgo a formal mention in the
forecast at this time.

Following a chilly start to the day on Thursday, increased
sunshine and a moderating airmass through the day will help push
inland temperatures back into the 60s to low 70s (warmest
across interior sections of northern IL). However, continued
onshore easterly winds across the northeastern IL Lake Michigan
shore will keep conditions along and near the lake in the 50s to
near 60. Dry weather is expected through the day. However,
scattered rain shower chances will return to the forecast later
Thursday night into Friday morning as the first of several mid-
level impulses ejecting out of the southwest CONUS begins to
move into the central CONUS.

While our area may experience a period of showers, and possibly
some storms (especially in the south), Thursday night into
Friday, the main focus for potentially more substantial showers
and thunderstorms in our area will be this weekend into early
next week. Deterministic and ensemble guidance remain in
agreement that a potent surface low tracking eastward across
southern Canada through late week will lay out a west-to-east
oriented quasi-stationary surface frontal boundary somewhere
across the Midwest into the lower Great Lakes region on
Saturday. This front may become the focus for a few of waves of
showers and thunderstorms this the weekend as the airmass south
of the front moistens and destabilizes. Thereafter, a more
pronounced upper trough digging into the western CONUS could
drive a stronger storm system northeastward from the Plains
through the Upper Midwest early next week. Such a system would
support very warm and breezy conditions across our area early
next week, along with continued chances of showers and
thunderstorms, some potentially severe with heavy rainfall.
Stay tuned!

KJB

&&

.AVIATION /12Z TAFS THROUGH 18Z THURSDAY/...
Issued at 620 AM CDT Wed May 13 2026

NNW winds will occasionally gust 20 to 25 knots through at
least early afternoon. A lake-enhanced NE wind shift with speeds
up to 15 knots is then expected to cross the Chicago terminals
sometime during the afternoon. Confidence in the exact timing
remains low as the boundary may stall near the terminals for
several hours this afternoon. It is quite possible that this
occurs between ORD and MDW, which would lead to an early
afternoon passage at MDW and late afternoon passage at ORD. By
late evening, winds will settle NW under 5 knots or become
calm/VRB as high pressure shifts over the area. Winds will then
shift NE under 10 knots late Thursday morning as the high
pressure exits to the east.

Areas of low-end VFR stratus will filter over the terminals
this morning. While there may be a few instances of the stratus
lowering to around 3kft/MVFR this morning, latest trends
indicate chances continue to decrease. Otherwise, the VFR
stratus will gradually lift this afternoon and dissipate
tonight.

Kluber

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 7 PM CDT this evening for the IL
     nearshore waters.

     Small Craft Advisory until 1 AM CDT Thursday for the IN
     nearshore waters.

&&

$$

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